Role of 5-HT in cholera toxin-induced mucin secretion in the rat small intestine

Am J Physiol. 1996 Jun;270(6 Pt 1):G1001-9. doi: 10.1152/ajpgi.1996.270.6.G1001.


We examined the role of 5-hydroxytryptamine (5-HT) in cholera toxin (CT)-induced mucin secretion in the proximal and distal regions of the rat small intestine. Neither the 5-HT2 receptor antagonist ketanserin nor the cyclooxygenase inhibitor indomethacin was capable of inhibiting choleraic mucin secretion. However, in the presence of the mixed 5-HT3/4 receptor antagonist tropisetron at doses that block both receptor subtypes, the secretory response was reduced to baseline levels in the proximal and distal small intestine. The selective 5-HT3 receptor antagonist ondansetron had no significant effect. These findings suggest that choleraic mucin secretion is mediated primarily through the activation of a 5-HT4-like receptor. Mucin secretion in response to the exogenous application of 5-HT occurs via two pathways: one is mediated by a 5-HT4-like receptor and is capsaicin sensitive but tetrodotoxin (TTX) insensitive, and one lacks the capsaicin-sensitive 5-HT4-mediated response but is TTX sensitive. Both converge on a common pathway that is cholinergic. No significant differences were observed between proximal and distal intestinal segments.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Capsaicin / pharmacology
  • Cholera Toxin / pharmacology*
  • Indoles / pharmacology
  • Intestine, Small / drug effects
  • Intestine, Small / metabolism*
  • Male
  • Mucins / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Serotonin / physiology*
  • Serotonin Antagonists / pharmacology
  • Tetrodotoxin / pharmacology
  • Tropisetron


  • Indoles
  • Mucins
  • Serotonin Antagonists
  • Serotonin
  • Tetrodotoxin
  • Tropisetron
  • Cholera Toxin
  • Capsaicin